1. Field of the Invention
The present invention relates to a rigid or soft gas permeable elastomer contact lens bonded with a titanium or oxide compounds thereof. The oxides of titanium include titanium monoxide (TiO), titanium dioxide (TiO.sub.2), dititanium trioxide (Ti.sub.2 O.sub.3), trititanium pentoxide (Ti.sub.3 O.sub.5), and mixtures thereof. The tritanium pentoxide species is the preferred entity. The titanium treated lens have high oxygen permeability, an improved wetting ability, a decreased fogging ability, an enhanced self-cleaning characteristic, and a decrease in the transmissibility of ultraviolet radiation.
The method of incorporating the additives is by cationic polymerization of either a coating of or in situ bonding to an elastomeric polymer resulting in the expression of the additive toward the exterior surface of the chemical matrix of the rigid contact lens. Other means of adding the additives to the elastomeric polymer include electron beam evaporation, sputtering and ion implantation
Initially, transparent rigid gas permeable contact lenses were based on silicon and methylmethacrylate polymers. Silicon increased the permeability and hydrophobic nature, but decreased. lens flexure, wettability and deposit resistance. Then, fluorine was added to silicon in the form of fluorosilicone acrylate to increase the permeability to oxygen, but bulk and surface properties of the lenses were compromised.
Dk is a measurement of the oxygen permeability of a contact lens. The higher the Dk value, the more oxygen permeable and more desirable the lens becomes. The addition of fluorine and silicon molecules increases the Dk value, but wettability decreases and lens flexure increases. For reduction of lens flexure, polymer chain mobility must be reduced by increasing cross-linkage.
Currently, optometrists continue to use a majority of contact lenses with lower Dk values, e.g., below 50, of silicon acrylate and fluorosilicone acrylate elastomers.
The problem of hydrophobicity with silicone elastomer lenses has been alleviated with surface treatment by plasma and radiation. However, when the contact lens is scratched the hydrophobic interior is exposed. Fogging and lack of protection from ultraviolet radiation of contact lenses are other problems.
There is a need for a contact lens wherein the aforementioned problems are minimized. The present invention is deemed to satisfy that need.
2. Description of the Related Art
The related art describes various compositions for use as contact lens. The art of interest will be discussed in the order of perceived relevance to the present invention.
Rong Wang et al., "Light-induced amphiphilic surfaces", Nature, Vol. 388, Jul. 31, 1997 pp. 431 and 432, describes the increased surface wettability of a glass substrate by coating with a hydrophilic and oleophilic titanium dioxide (anatase) surface and subjecting the composition to ultraviolet irradiation. The coating was first annealed at 773 K. and irradiated to increase the water-contact angle from 72.degree..+-.1.degree. to 0.degree..+-.1.degree.. Polycrystals and single crystals of anatase or rutile titanium dioxide were utilized. Long term storage in the dark results in the substitution of oxygen from air for the chemisorbed hydroxyl groups. This reference does not suggest the use of the coating on any other hard non-glass substrate, let alone a medically safe polymeric substrate such as a rigid contact lens.
U.S. Pat. No. 2,717,246 issued on Sep. 6, 1955, to Roy H. Kienle et al. describes a titanium dioxide pigment coated with layers of a hydrous oxide and a polysiloxane useful in printing inks to make them water repellant. This teaching is negative, because the present invention incorporates titanium or its oxide in a polysiloxane and other polymers to increase the wetting property of the rigid lens coating.
U.S. Pat. No. 5,310,571 issued on May 10, 1994, to David Meadows describes a chemical treatment method to improve oxygen permeability through and protein deposition on hydrophilic (soft) and rigid gas permeable contact lenses. The hydrated polymer lens is purged of all water and oxygen, and the lens is treated by a fluorine-containing gas under non-plasma conditions for replacement of all hydrogen atoms in the polymer. This method is distinguished by its reliance on treatment by fluorine in a non-plasma environment and the lack of titanium or oxides thereof.
U.S. Pat. No. 5,091,204 issued on Feb. 25, 1992, to Buddy D. Ratner et al. describes the modification of an intraocular lens made of poly methyl methacrylate by plasma deposition of a gaseous perfluoropropane monomer to deposit an impermeable coating of fluoropolymer on the lens. This patent similarly treats a polymer surface with fluorine to obtain an impermeable coating, but lacks any suggestion for adding titanium or oxides thereof in the present invention.
U.S. Pat. No. 4,143,949 issued on Mar. 13, 1979, to Richard V. Chen describes a process for depositing a hydrophilic polymethacrylate coating having a thickness of 50-20,000 Angstroms on hard and soft contact lens by a plasma glow discharge method with parameters such as a pressure of 100-500 millitorricelli and an electromagnetic frequency of about 15.6 megahertz. This patent does not suggest the addition of titanium or its oxides.
U.S. Pat. No. 4,686,267 issued on Aug. 11, 1987, to Edward J. Ellis et al. describes fluorine containing siloxane polymeric contact lens compositions with a hardness of at least 90 on the Rockwell R scale. This patent does not suggest the addition of titanium or its oxides.
U.S. Pat. No. 3,347,816 issued on Oct. 17, 1967, to Walter Krauss et al. describes the addition of rutile titanium dioxide pigment to polysiloxane for forming glossy coatings of increased thermal stability on sheet metal plates. There is no suggestion for coating contact lens.
U.S. Pat. No. 3,697,475 issued on Oct. 10, 1972, to Horton H. Morris et al. describes a white thermoplastic paper containing an organo titanate compound having use in laminates, non-woven fabric and rug backing. There is no suggestion for coating contact lens.
Germany Patent No. 3,407,087 issued on Sep. 5, 1985, to Gottfried Phillipp et al. describes a scratch resistant coating for metal, plastics, ceramic, wood or glass obtained by hydrolytic condensation of titanium or zirconium compounds and organo-silane compounds. There is no suggestion for coating contact lens.
U.S. Pat. No. 4,246,389 issued on Jan. 20, 1981 to Albert R. LeBoeuf describes a soft contact lens composition based on acrylic siloxanes having increased oxygen permeability. There is no suggestion for adding titanium or oxides thereof to the soft contact lens.
U.S. Pat. No. 3,057,822 issued on Oct. 9, 1962, to John B. Rust et al. describes organo silicon-titanium copolymers which have high temperature and pressure resistance. The product is useful as laminating resins, insulating varnishes, and filler materials. There is no suggestion for adding to contact lenses.
U.S. Pat. No. 3,035,071 issued on May 15, 1962 to John H. Haslam describes a titanium acylate silicone copolymer useful as coating compositions, lubricating oil detergents, and water repellents. There is no suggestion for adding to contact lenses.
U.K. Patent Application No. 1,205,767 published on Sep. 16, 1970, for the National Patent Development Corporation describes non-fogging coatings for glass or plastics material such as a camera lens. The coating composition comprises a homopolymer of a water-soluble hydroxy-alkyl acrylate or hydroxy-alkyl methacrylate, or a copolymer of a major amount of the water-soluble hydroxyalkyl acrylate or hydroxyalkyl methacrylate and a minor amount of a poly-functional cross-linking monomer which are hydrophilic. There is no suggestion for coating contact lenses.
U.K. Patent Application No. 927,202 published on May 29, 1963, for the Dow Corning Corporation describes polymethyl methacrylate and silicone rubber contact lenses more hydrophilic by coating with a protein or a polysaccharide. There is no teaching for adding titanium or oxides thereof to the lenses.
U.K. Patent No. Application No. 1,229,608 published on Apr. 28, 1971, for the Dow Corning Corporation describes rubber elastomers for contact lenses. There is no teaching for adding titanium or oxides thereof to the lenses.
The organic polymers described by the relevant art are hereby incorporated by reference herein.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus, a soft or rigid oxygen gas permeable silicon elastomer contact lens with enhanced wetting and cleaning ability, and decreased fogging and transmissibility of ultraviolet radiation will be shown solving the aforementioned problems.